Electric pump and motor

ABSTRACT

The present invention provides A motor comprising: a shaft; a rotor including a hole in which the shaft is disposed; and a stator outside the rotor, wherein the rotor comprises a rotor core and a magnet, wherein the rotor core comprises: a main body; a pocket which is formed in the main body and in which the magnet is disposed; first barriers extending from both sides of the pocket; and second barriers formed between an inner circumferential surface of the main body and an outer circumferential surface of the main body, wherein a center (C11) of the second barrier has a certain arrangement angle (θ) in a circumferential direction from a first line (L11) passing through a center (CC) of the main body and a center of a width (W) of the magnet.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a Continuation of U.S. application Ser. No.16/643,670, filed Mar. 2, 2020, which is a U.S. National StageApplication under 35 U.S.C. § 371 of PCT Application No.PCT/KR2018/009004, filed Aug. 8, 2018, which claims priority to KoreanPatent Application Nos. 10-2017-0117159, filed Sep. 13, 2017,10-2017-0117930, filed Sep. 14, 2017, 10-2017-0118455, filed Sep. 15,2017 and 10-2017-0118456, filed Sep. 15, 2017, whose entire disclosuresare hereby incorporated by reference.

TECHNICAL FIELD

Embodiments relate to an electric pump and a motor.

BACKGROUND ART

In general, an electric oil pump (EOP) is a device that supplies oil toa hydraulic line of a transmission or a braking device of a vehicleusing a motor, in which circulation of oil is necessary.

In the case of a hybrid electric vehicle (HEV), an engine is stoppedwhen the vehicle is stopped and thus it is difficult to supply aconstant pressure to a transmission through a mechanical oil pump.Therefore, the HEV employs an electric oil pump that supplies oilthrough a motor.

Such an electric oil pump includes a suction port and a discharge portthrough which oil moves.

However, in an electric oil pump of the related art, a phenomenon occursin which flow rate performance decreases sharply at a high flow rate anda flow rate is not uniform during the movement of a fluid.

A motor is a device that converts electrical energy into mechanicalenergy to generate a turning force and has been widely used in vehicles,household appliances, industrial equipment, and the like.

The motor may include a housing, a shaft, a stator disposed on an innercircumferential surface of the housing, a rotor installed on an outercircumferential surface of the shaft, and the like. Here, the stator ofthe motor causes electrical interaction with the rotor to inducerotation of the rotor.

Here, the rotor may be classified into a surface-mounted permanentmagnet (SPM) type and an interior permanent magnet (IPM) type accordingto a coupling structure of a magnet installed in the rotor core.

In an IPM type rotor, a magnet is inserted into a rotor core and thusmagnetic flux density is lower than that of an SPM type rotor in which amagnet is exposed on a surface thereof, and therefore, dynamiccharacteristics of a motor having the IPM type rotor may be lower thanthose of a motor having the SPM type rotor.

In particular, when barriers are formed at both sides of the magnet inthe IPM type rotor, an H-field indicating the magnitude of a magneticflux is low at inner corners of the magnet. Accordingly, when amagnetization process is performed after assembly of the magnet, HScharacteristics indicating the strength of a magnetic force may not besatisfied and thus full magnetization cannot be achieved. In addition,when the motor is operated at a high temperature, a risk of irreversibledemagnetization may occur additionally.

When the H-field is increased to satisfy the HS characteristics of themagnet so as to solve the above problems, an overcurrent may be suppliedand thus a magnetizer and a magnetization yoke may be degraded.

Therefore, there is a need for a rotor which achieves full saturatedmagnetization of a magnet only with a certain amount of current withoutapplying an overcurrent.

DISCLOSURE Technical Problem

Embodiments are directed to providing an electric pump in which a shapeof a suction port is changed to stabilize a flow of a fluid.

Embodiments are also directed to providing an electric pump capable ofbeing detachably coupled with a bus bar through a fork-type terminal.

Embodiments are also directed to providing an electric pump in which amotor housing and a connector unit are connectable at accuratepositions.

Other embodiments of the present invention are directed to providing amotor in which barriers are formed on a rotor core to achieve fullmagnetization of a magnet.

Other embodiments are directed to providing a motor in which anarrangement position of a barrier is determined by an arrangement angleand distance relative to a central point.

Aspects of the present invention are not limited thereto and otheraspects not mentioned herein will be clearly understood by those ofordinary skill in the art from the following description.

Technical Solution

According to one aspect of the present invention, an electric pumpincludes a motor unit which includes a shaft, a rotor coupled to theshaft, and a stator disposed outside the rotor; a pump unit whichincludes a first rotor coupled to the motor unit and including a firstlobe having gear teeth, and a second rotor disposed outside the firstrotor and including a second lobe; and a second cover including a secondsurface on which the pump unit is disposed, wherein a second suctionport and a second discharge port are disposed on the second surface, thesecond suction port provided on the second surface includes a thirdprotrusion protruding toward an inner side of the second suction port,and an angle formed by a first line connecting the center of the firstrotor and the center of the second rotor and a second line connectingthe center of the first rotor and a distal end of the third protrusionis inversely proportional to the number of gear teeth of the first lobe.

The first line passing through the center of the first rotor and thecenter of the second rotor may be parallel to a third line connectingends of the second suction port in a region adjacent to the thirdprotrusion.

A distance between the first line and the second line may beproportional to a distance between the center of the first rotor and thecenter of the second rotor.

A first cover may be disposed between the motor unit and the pump unit,the first cover may include a first surface which accommodates the pumpunit, the first surface may include a first suction port and a firstdischarge port, and the first suction port and the second suction portmay have different shapes.

The second cover may include an inlet which communicates with the secondsuction port and an outlet which communicates with the second dischargeport.

A third coupling hole may be formed in the center of the first rotor andengaged with the shaft, the shaft may have at least one cut surface, andthe cut surface may match in shape with the third coupling hole.

According to another aspect of the present invention, an electric pumpincludes a motor unit including a shaft, a rotor provided with theshaft, a stator disposed outside the rotor, a bus bar disposed above thestator, and a motor housing which accommodates the rotor and the stator;and a connector unit disposed on the motor unit and including a powerterminal coupled to a terminal of the bus bar, wherein the bus barincludes a bus bar terminal coupled with a coil wound around the statoror the rotor, and a bus bar body which insulates the bus bar terminal,an end of the power terminal diverges into a pair of contact portions,and the bus bar terminal is inserted between the contact portions to beelectrically connected to the contact portions.

Divergence areas of the pair of contact portions may include a curvedsurface.

Each of the pair of contact portions may include a first region, a widthof which increases at the divergence area; a second region which extendsfrom the first region and a width of which decreases; and a third regionwhich extends from the second region and a width of which increases,wherein a point at which the second region and the third region areconnected to each other is in contact with the bus bar body.

The third region may include a curved surface.

The bus bar body may include a pair of first protrusions which guide thepair of contact portions.

The bus bar terminal may include a curved portion and be in surfacecontact with the pair of contact portions.

According to another aspect of the present invention, an electric pumpincludes a motor unit including a shaft, a rotor coupled to the shaft, astator disposed outside the rotor, and a motor housing whichaccommodates the rotor and the stator; and a connector unit disposed onthe motor unit, wherein the motor unit includes at least one hole, andthe connector unit includes at least one second protrusion inserted intothe at least one hole.

An end portion of the motor housing may include a protrusion having acertain area, the connector unit may include a connector body and aconnector connection part facing the protrusion, the protrusion may beprovided with the at least one hole, and the connector connection partmay be provided with the at least one second protrusion inserted intothe at least one hole.

The connector connection part may be connected to a side of theconnector body and include a first connection portion on which the atleast one second protrusion is disposed and a second connection portionconnected at a certain angle to the first connection portion.

The connector connection part may include a plurality of groovesarranged such that opposite sides thereof are symmetric to each other,and the at least one second protrusion may be provided between theplurality of grooves.

The connector connection part may include a rib formed in a lengthwisedirection, and the at least one second protrusion may be provided on therib.

The at least one second protrusion may be provided in a cylindricalshape, and an upper end thereof may be inclined along a circumference ofthe at least one second protrusion.

According to another aspect of the present invention, a motor includes ashaft, a rotor including a hole in which the shaft is disposed, and astator outside the rotor, wherein the rotor includes a rotor core and amagnet, the rotor core includes a main body, a pocket which is formed inthe main body and in which the magnet is disposed, first barriersextending from both sides of the pocket, and second barriers formedbetween an inner circumferential surface of the main body and an outercircumferential surface of the main body, and a center (C11) of thesecond barrier has a certain arrangement angle θ in a circumferentialdirection from a first line (L11) passing through a center (CC) of themain body and a center of a width (W) of the magnet.

The arrangement angle θ may be calculated by the following equation:

${{\arctan\left( \frac{W/2}{D11} \right)} \leq \theta \leq {\arctan\left( \frac{W/2}{D22} \right)}},$

wherein W represents a width of the magnet, D11 represents a distancefrom the center of the main body to an inner side surface of the magnet,and D22 represents a distance from the center of the main body to anouter side surface of the magnet.

The second barrier may have a certain radius (R).

The inner side surface of the magnet may be disposed on a second line(L22) passing through the center (CC) of the main body and the center(C11) of the second barrier.

An arrangement distance D33 from the center (CC) of the main body to thecenter (C11) of the second barrier may be calculated by the followingequation:

${{{D33} = \frac{D11}{\cos\theta}} - O - R},$

wherein O represents a distance between one point (P1) on an outercircumferential surface of the second barrier disposed on the secondline (L22) and one point P2 on the inner side surface of the magnet.

The second barrier may be formed to be long from an upper end of themain body to a lower end of the main body.

Two of the second barriers disposed to correspond to one magnet may besymmetrical to each other with respect to the first line (L11).

Advantageous Effects

According to an embodiment, flow rate performance can be achieved evenat a high flow rate.

Noise can be reduced by stabilizing the flow of a fluid.

Durability of a product can be increased by minimizing bubbles to beintroduced into a region in which a fluid flows.

An additional process or structure for connecting a terminal and a busbar of a motor can be skipped to reduce an assembly time and costs.

Components are replaceable by applying a detachable structure.

The reliability of assembly of a terminal and a bus bar may be securedusing a position guide.

A connector unit can be connected at a designated position, therebyminimizing performance deviation for each product.

A manufacturing method can be simplified and process investment costscan be reduced by simplifying a shape of a motor housing for fixing aposition.

In addition, in a motor according to another embodiment of the presentinvention, a second barrier can be formed in a rotor to adjust magneticflux saturation of a rotor core during magnetization of a magnet.Accordingly, when the same current is supplied for magnetization, fullmagnetization of the magnet can be achieved by allowing a maximum Hfield in a region of the magnet.

In this case, an arrangement position of the second barrier on the rotorcore can be adjusted by an arrangement angle and distance.

Various and beneficial advantages and effects of the present inventionare not limited to the above description and will be more easilyunderstood in the course of describing specific embodiments of thepresent invention.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an electric pump according to anembodiment of the present invention.

FIG. 2 is an exploded perspective view of FIG. 1 ,

FIG. 3 is a diagram illustrating a structure of a motor unit which is acomponent of FIG. 1 ,

FIG. 4 is a diagram illustrating a structure of a bus bar which is acomponent of FIG. 1 ,

FIG. 5 is a diagram illustrating a structure of a connector unit whichis a component of FIG. 1 ,

FIG. 6 is a diagram illustrating an arrangement of power terminalsincluded in the connector unit which is a component of FIG. 1 ,

FIG. 7 is a diagram illustrating a structure in which the bus bar andthe power terminals of FIG. 1 are connected to each other,

FIG. 8 is a diagram illustrating a structure of an end portion of thepower terminal of FIG. 7 ,

FIG. 9 illustrates a bus bar terminal which is coupled to the powerterminal in FIG. 7 according to an embodiment,

FIG. 10 is a diagram illustrating a structure in which a motor housingand a connector unit of FIG. 2 are connected to each other,

FIG. 11 is a diagram illustrating a first suction port and a firstdischarge port formed in a first cover of FIG. 2 ,

FIG. 12 is a diagram illustrating a second suction port and a seconddischarge port formed in a second cover of FIG. 2 ,

FIG. 13 is a diagram illustrating a structure of a pump unit in FIG. 2 ,

FIG. 14 is a diagram illustrating a state in which the pump unit islocated on the first cover,

FIG. 15 is a diagram illustrating a state in which the pump unit islocated on the second cover,

FIG. 16 is a diagram showing a change in flow rate performance when ashape of the second cover of FIG. 15 is applied,

FIG. 17 is a longitudinal sectional view of a motor according to theembodiment,

FIG. 18 is a cross-sectional view taken along line A-A of FIG. 17 ,

FIG. 19 is a diagram illustrating a rotor core of a motor according toan embodiment,

FIG. 20 is a diagram illustrating region B of FIG. 18 ,

FIG. 21 is a diagram illustrating various embodiments of a secondbarrier of a rotor disposed in a motor according to an embodiment,

FIG. 22A and FIG. 22B are diagrams showing a comparison of an H field ofa rotor of a motor according to an embodiment with an H field of a rotorof a motor according to a comparative example,

FIG. 23A and FIG. 23B are diagrams showing a comparison of a uniformmagnetic flux line of a rotor of a motor according to an example with auniform magnetic flux line of a rotor of a motor according to acomparative example,

FIG. 24A and FIG. 24B are diagrams showing a comparison of magnetic fluxdensity of a rotor of a motor according to an example with magnetic fluxdensity of a rotor of a motor according to a comparative example.

MODES OF THE INVENTION

Various changes may be made in the present invention and variousembodiments may be implemented, and certain embodiments will beillustrated in the drawings and described hereinafter. However, itshould be understood that embodiments of the present invention are notlimited to these embodiments and cover all modifications, equivalents,and alternatives falling within the idea and scope of embodiments.

As used herein, the terms “first,” “second,” etc. may be used herein todescribe various elements but these elements are not limited by theseterms. These terms are used only for the purpose of distinguishing oneelement from another. For example, a second element discussed belowcould be termed a first element without departing from the scope ofembodiments. Similarly, a first element could be termed a secondelement. The terms “and/or” includes any one or any combination of aplurality of related listed items.

The terminology used herein is for the purpose of describing certainembodiments only and is not intended to be limiting of embodiments ofthe present invention. As used herein, the singular expressions areintended to include plural forms as well, unless the context clearlydictates otherwise. It will understood that the terms “comprise” and/or“comprising,” when used herein, specify the presence of stated features,integers, steps, operations, elements, components, or a combinationthereof but do not preclude the presence or addition of one or morefeatures, integers, steps, operations, elements, components, or acombination thereof.

When one element is referred to as being formed “on” or “under” anotherelement in embodiments, it will be understood that the two elements areformed to be in direct contact with each other or to be in indirectcontact with each other while one or more elements are interposedtherebetween. The expression “on or under one element” should beunderstood to mean not only an upward direction but also a downwarddirection with respect to the element.

Hereinafter, embodiments will be described in detail with reference tothe accompanying drawings, and the same or corresponding components willbe denoted by the same reference numerals regardless of figure numberand will not be redundantly described.

FIGS. 1 to 16 clearly illustrate only main features for conceptuallyclear understanding of the present invention, and thus, it is expectedthat various modifications may be made in the drawings and the scope ofthe present invention should not be limited by specific shapes shown inthe drawings.

FIG. 1 is a perspective view of an electric pump according to anembodiment of the present invention. FIG. 2 is an exploded perspectiveview of FIG. 1 .

Referring to FIGS. 1 and 2 , the electric pump according to theembodiment of the present invention may include a motor unit 100, aconnector unit 200, a first cover 300, a pump unit 400, and a secondcover 500.

The motor unit 100 generates power to transfer the power to the electricpump, and the connector unit 200 is provided on the motor unit 100 tosupply the power to the motor unit 100.

The connector unit 200 is provided on the motor unit 100 and may includea connector body 210 on a motor housing 150 and a connector connectionpart 230 connected to a side of the connector body 210. A first throughhole 211 may be provided, through which a shaft 110 of the motor unit100 passes.

The first cover 300 is disposed between the connector unit 200 and thepump unit 400 and includes a second through hole 340 through which theshaft 110 of the motor unit 100 passes.

The pump unit 400 may be disposed between the first cover 300 and thesecond cover 500 and may be provided with a third through hole to whichthe shaft 110 passing through the first cover 300 is coupled.

The second cover 500 may be disposed on a front side of the pump unit400 and combined with the first cover 300 to accommodate the pump unit400.

FIG. 3 is a diagram illustrating a structure of the motor unit 100 ofFIG. 1 .

Referring to FIG. 3 , the motor unit 100 transmits power to the pumpunit 400 and includes the shaft 110, a rotor 120, a stator 130, a busbar 140, and a motor housing 150.

The shaft 110 may be coupled to the rotor 120. When power is supplied tocause electromagnetic interaction between the rotor 120 and the stator130, the rotor 120 rotates and the shaft 110 rotates in connectiontherewith. The shaft 110 may be supported by a bearing.

The rotor 120 is disposed inside the stator 130. The rotor 120 mayinclude a rotor core and a magnet coupled to the rotor core. The rotor120 may be classified into the following types according to a couplingmethod of the rotor core and the magnet.

The rotor 120 may be embodied as a type in which the magnet is coupledto an outer circumferential surface of the rotor core. In this type ofthe rotor 120, a separate can member may be coupled to the rotor core toprevent separation of the magnet and increase the coupling of themagnet. Alternatively, the magnet and the rotor core may be doubleinjected and integrally formed.

The rotor 120 may embodied as a type in which the magnet is coupled tothe inside of the rotor core. In this type of the rotor 120, the insideof the rotor core may be provided with a pocket into which the magnet isinserted.

There may be two types of rotor core.

First, a rotor core may be formed by stacking a plurality of thin steelplates together. In this case, the rotor core may be formed as one piecethat does not form a skew angle or as a form in which a plurality ofunit cores forming a skew angle are combined together.

Secondly, a rotor core may be in the form of a single container. In thiscase, the rotor core may be formed as one piece that does not form askew angle or as a form in which a plurality of unit cores forming askew angle are combined together.

A magnet may be included inside or outside each of the unit cores.

The stator 130 causes electrical interaction with the rotor 120 toinduce the rotation of the rotor 120. A coil 131 may be wound around thestator 130 to cause interaction with the rotor 120. A specificconfiguration of the stator 130 for winding a coil around the stator 30will be described below.

The stator 130 may include a stator core with teeth. The stator core maybe provided with a ring-shaped yoke and teeth may be provided on theyoke to face the center of the stator core. The teeth may be providedaround the yoke at regular intervals. The stator core may be formed bystacking a plurality of thin steel plates together. Alternatively, thestator core may be formed by coupling or connecting a plurality ofdivided cores to each other.

The bus bar 140 may be disposed on an upper end of the stator 130 to beelectrically connected to the coil 131. The bus bar 140 may include abus bar body 141 and a bus bar terminal 143. The bus bar body 141 may beembodied as a ring-shaped mold member. The bus bar terminal 143 isconnected to an end of the coil 131 lifted from an assembly of thestator 130 or an assembly of the rotor 120.

The bus bar 140 may electrically connect coils 131 wound around thestator 130 or the rotor 120 to be electrically connected to U-, V-, orW-phase power terminals 250.

The motor housing 150 may be formed in a cylindrical shape such that thestator 130 may be coupled to an inner wall thereof. An upper portion ofthe motor housing 150 may be open and a lower portion thereof may beclosed. The lower portion of the motor housing 150 may be provided witha bearing mounting space for accommodating a bearing for supporting thelower portion of the shaft 110.

FIG. 4 is a diagram illustrating a structure of the bus bar 140 of FIG.1 .

The bus bar terminal 143 may be formed as an arc and include a pluralityof connection terminals 143 a to be coupled to the coil 131. In oneembodiment, three bus bar terminals 143 may be provided to electricallyconnect the coil 131 wound around the stator 130, and each of the threebus bar terminals 143 may be delta-connected.

FIG. 5 is a diagram illustrating a structure of the connector unit 200of FIG. 1 . FIG. 6 is a diagram illustrating an arrangement of the powerterminals 250 included in the connector unit 200 of FIG. 1 .

Referring to FIGS. 5 and 6 , the connector unit 200 may include aconnector body 210 disposed on the motor unit 100 and a connectorconnection part 230 connected to a side of the body of the connectorunit 200 to receive power.

The connector body 210 may be provided with the first through hole 211through which the shaft 110 passes, and a region thereof may be insertedinto the motor housing 150. A sealing part may be provided at a side ofthe connector body 210 to maintain airtight coupling of the connectorbody 210 with the motor housing 150.

A plurality of power terminals 250 may protrude outward from theconnector body 210. In one embodiment, three power terminals 250 may beprovided to be each electrically connected to one of the bus barterminals 143.

The connector connection part 230 is connected to the connector body 210and may receive external power. In one embodiment, the power terminals250 protruding outward from the connector body 210 may be provided in abent shape to pass through the connector body 210 and the connectorconnection part 230. The shape of the power terminals 250 is not limitedand may be variously changed according to the shape of the connectorconnection part 230 connected to the connector body 210.

FIG. 7 is a diagram illustrating a structure in which the bus bar 140and the power terminals 250 of FIG. 1 are connected to each other. FIG.8 is a diagram illustrating a structure of an end portion of the powerterminal 250 of FIG. 7 .

Referring to FIGS. 7 and 8 , bus bar terminals 143 may be inserted intothe power terminals 250 to be electrically connected to the powerterminals 250.

An end of each of the power terminals 250 may branch into a pair ofcontact portions 251. Ends of the pair of contact portions 251 arespaced apart from each other, and the bus bar terminal 143 may beinserted into a space between the pair of contact portions 251. Adistance d1 between the ends of the pair of contact portions 251 spacedapart from each other may be less than a width of the bus bar terminal143 and may be elastically deformed when the bus bar terminal 143 isinserted between the pair of contact portions 251.

In one embodiment, the distance d1 between the pair of contact portions251 increases in a first region A1 starting from a point where the powerterminal 250 branches, decreases in a second region A2, and increasesagain in a third region A3. The pair of contact portions 251 aredesigned according to a stress analysis result to prevent cracks fromoccurring due to an expansion force applied when the pair of contactportions 251 are spread apart to be brought into contact with the busbar terminal 143. As the stress analysis result, damage caused by stressmay be minimized by setting, to a curved region, a branch region X1 towhich maximum stress is applied.

A section changed from the second region A2 to the third region A3 is incontact with the bus bar terminal 143, and the third region A3 mayinclude a curved portion to facilitate the insertion of the bus barterminal 143.

The bus bar body 141 may be provided with a plurality of firstprotrusions 141 a to guide the position of the pair of contact portions251. The first protrusions 141 a may be arranged in pairs and protrudeupward from the bus bar body 141.

The pairs of first protrusions 141 a may be spaced apart from eachother, and the bus bar terminal 143 may pass between the firstprotrusions 141 a. The power terminal 250 may be inserted between thefirst protrusions 141 a, and the bus bar terminal 143 passing betweenthe first protrusions 141 a may be inserted into the contact portions251 to be in contact with the contact portions 251.

The first protrusions 141 a may not only guide the position of the busbar terminal 143 but also prevent the separation or movement of thecontact portions 251 in contact with the bus bar terminal 143 tomaintain an electrically stable contact. A shape of the firstprotrusions 141 a is not limited but may be changed in various shapes tosupport both sides of the contact portions 251.

FIG. 9 illustrates the bus bar terminal 143 which is coupled to thepower terminal in FIG. 7 according to an embodiment.

Referring to FIG. 9 , both sides of the bus bar terminal 143 in contactwith the contact portions 251 may include a curved portion 143 b. Thecurved portion 143 b may be provided to match in shape to a contact sideof the contact portion 251 in contact therewith in a curved form.

The curved portion 143 b may facilitate the insertion of the contactportion 251 into the bus bar terminal 143 and maintain a stable couplingstate by increasing a contact area through shape matching.

FIG. 10 is a diagram illustrating a structure in which the motor housing150 and the connector unit 200 of FIG. 2 are connected to each other.

Referring to FIG. 10 , the connector unit 200, which is a component ofthe present invention, may be disposed on the motor housing 150. Variouscomponents, such as the power terminal 250, a substrate, and ahall-integrated circuit (IC), are disposed on the connector unit 200 anda position thereof should be fixed when the power terminal 250 iscombined with the motor unit 100.

In the present invention, in order to fix the position of the connectorunit 200, the motor housing 150 may be provided with at least one hole151 a and the connector unit 200 may be provided with at least onesecond protrusion 231 a. The positions of the hole 151 a and the secondprotrusion 231 a may respectively intersect those of the connector unit200 and the motor housing 150, and a description about the formation ofthe hole 151 a in the connector unit 200 and the formation of the secondprotrusion 231 a on the motor housing 150 will be omitted.

A protrusion 151 may be provided on a side of the motor housing 150. Theprotrusion 151 may extend from an upper portion of the motor housing150, and the hole 151 a may be formed in a region of a center of theprotrusion 151. A shape of the hole 151 a is not limited but may havethe same cross-sectional shape as the second protrusion 231 a so thatthe second protrusion 231 a of the connector unit 200 may be insertedinto the hole 151 a.

The connector connection part 230 may include a first connection portion231 and a second connection portion 233.

The first connection portion 231 is connected to a side of the connectorbody 210 and is disposed to face the protrusion 151 when the connectorconnection part 230 and the motor housing 150 are coupled to each other.In this case, the first connector portion 231 may be provided with thesecond protrusion 231 a, and the second protrusion 231 a may be insertedinto the hole 151 a to fix the position of the connector unit 200.

In one embodiment, the second protrusion 231 a may be provided in acylindrical shape, the upper portion of which is inclined to be easilyinserted into the hole 151 a.

In addition, the first connector portion 231 may be provided with a rib231 b in a region at the center thereof, and the second protrusion 231 amay be disposed on the rib 231 b. The rib 231 b may be arranged in aspecific structure or may be formed by coring a basic structure. The rib231 b may be disposed in a lengthwise direction of the first connectionportion 231 to resist bending or warping of the first connection portion231.

A plurality of grooves 231 c may be provided at both sides of the secondprotrusion 231 a of the first connection portion 231. In one embodiment,the plurality of grooves 231 c may be arranged at regular intervals andin a direction perpendicular to a direction of the rib 231 b.

The second connection portion 233 may be connected to the firstconnection portion 231 to receive external power. In one embodiment, thesecond connection portion 233 may be connected at a certain angle to thefirst connection portion 231. An angle at which the second connectionportion 233 and the first connection portion 231 are connected to eachother may be modified according to an angle at which the secondconnection portion 233 is installed to receive power.

FIG. 11 is a diagram illustrating a first suction port 320 and a firstdischarge port 330 formed in the first cover 300 of FIG. 2 . FIG. 12 isa diagram illustrating a second suction port 520 and a second dischargeport 530 formed in the second cover 500 of FIG. 2 . FIG. 13 is a diagramillustrating a structure of the pump unit 400 of FIG. 2 . FIG. 14 is adiagram illustrating a state in which the pump unit 400 is positioned inthe first cover 300. FIG. 15 is a diagram illustrating the pump unit 400is positioned in the second cover 500.

Referring to FIGS. 11 to 15 , the pump unit 400 may be disposed betweenthe first cover 300 and the second cover 500.

The pump unit 400 is inserted into a space, to which a fluid issupplied, between the second cover 500 and the first cover 300 and pumpsoil by receiving power from the motor unit 100. The first cover 300 andthe second cover 500 are combined together to form a space in which thepump unit 400 is located. The first cover 300 and the second cover 500are described separately according to functional characteristics but maybe connected integrally to each other.

One side of the first cover 300 may be in contact with the connectorunit 200 and the other side thereof may include a first side 310 foraccommodating the pump unit 400.

The first side 310 may include the first suction port 320 and the firstdischarge port 330. The first suction port 320 and the first dischargeport 330 may each have a conventional port shape.

The second cover 500 may include a second side 510 on which the pumpunit 400 is disposed, and the second side 510 may include the secondsuction port 520 and the second discharge port 530. The second suctionport 520 may include an inlet 521, which communicates with the secondsuction port 520 and through which oil is introduced, and an outlet 531which communicates with the second discharge port 530.

The second suction port 520 and the second discharge port 530 may beformed in an arc shape and provided to be tapered from one side to theother side. In addition, the second suction port 520 and the seconddischarge port 530 may be arranged such that a wider portion of thesecond suction port 520 faces a wider portion of the second dischargeport 530 and a narrower portion of the second suction port 520 faces anarrower portion of the second discharge port 530.

The second discharge port 530 may have a conventional port shape.

The second suction port 520 may include a third protrusion 523protruding inward. The third protrusion 523 may protrude toward a spaceforming the second suction port 520 from an end of the second suctionport 520 farther from the center of the first rotor 410 among ends ofthe second suction port 520.

The suction port and discharge port are formed respectively on the firstcover 300 and the second cover 500 to guide a fluid to be smoothlysuctioned and discharged by the pump unit 400. These suction port anddischarge ports are arranged by partitioning a space. This is to preventmovement of the fluid due to a pressure difference.

Referring to FIG. 13 , the pump unit 400 is disposed between the firstcover 300 and the second cover 500 and pumps a fluid by receiving powerfrom the motor unit 100. The pump unit 400 may include the first rotor410 and the second rotor 120. The first rotor 410 may be referred to asan inner rotor 120 and the second rotor 430 may be referred to as anouter rotor 120.

A turning force is directly applied to the first rotor 410 from themotor unit 100 because the shaft 110 is coupled to a central portion ofthe first rotor 410. In one embodiment, the shaft 110 includes at leastone cut surface 111 and may be inserted into a third coupling hole 440formed in the center of the first rotor 410. The third coupling hole 440may match in shape with the shaft 110 to which the third coupling hole440 is inserted, thereby preventing the first rotor 410 from runningidle during rotation of the shaft 110.

The second rotor 430 is disposed outside the first rotor 410. Inaddition, in the first rotor 410, a first lobe 411 with N gear teethfacing outward in a radial direction with respect to the center ofrotation may be provided in a circumferential direction. The secondrotor 430 may be provided with N+1 second lobes 431 facing inward in theradial direction. In this case, the second lobe 431 may be disposed tobe caught by the first lobe 411. As the first rotor 410 rotates, thesecond rotor 430 rotates in connection with the first rotor 410.

Meanwhile, a diameter of a dedendum circle C1 of the first rotor 410(hereinafter referred to as “D1”) and a diameter of a dedendum circle C2of the second rotor 430 (hereinafter referred to as “D2”) are criteriafor forming a space for pumping oil.

In the present invention, oil may be stably supplied in high-speedregions by changing the shape of a suction port.

FIG. 14 illustrates a contact structure between the first suction port320 and the first discharge port 330 which are formed on the first cover300, similarly to a structure of the related art.

However, when the first cover 300 and the second cover 500 are combinedtogether, the first suction port 320 and the second suction port 520face each other and the first discharge port 330 and the seconddischarge port 530 face each other. In this case, the first suction port320 and the second suction port 520 may be arranged in different shapes.

Referring to FIG. 15 , the first rotor 410 and the second rotor 430 maybe disposed such that the centers thereof do not coincide with eachother. When a center P1 of the first rotor 410 and a center P2 of thesecond rotor 430 are projected onto the second cover 500, an angleformed by a first line L1 connecting the center P1 of the first rotor410 and the center P2 of the second rotor 430 and a second line L2connecting the center P1 of the first rotor 410 and an end of the thirdprotrusion 523 may be inversely proportional to the number of gearteeth. A flow rate and velocity of a fluid to be introduced may bedetermined by an arrangement position of the third protrusion 523.

In one embodiment, an angle θ formed by the first line L1 and the secondline L2 may be calculated by Equation 1 below.

$\begin{matrix}{\theta = \frac{360W}{N*2}} & \left\lbrack {{Equation}1} \right\rbrack\end{matrix}$

Here, N represents the number of gear teeth formed on the first rotor410.

The position of the end of the third protrusion 523 may be determinedaccording to the angle θ formed by the first line L1 and the second lineL2.

In one embodiment, when the first rotor 410 includes five gear teeth asillustrated in FIG. 13 , θ may be set to 36 degrees.

In this case, θ may be changed within a range of 5%.

A third line L3 connecting ends of the second suction port 520 in aregion adjacent to the third protrusion 523 may be parallel to the firstline L1. Two recessed regions are formed at ends of the second suctionport 520 due to the third protrusion 523 formed inside the secondsuction port 520, and the third line L3 connects innermost sides of thetwo recessed regions.

In addition, when the first line L1 and the third line L3 are parallelto each other, a distance d2 between the first line L1 and the thirdline L3 is proportional to a distance between the center P1 of the firstrotor 410 and the center P2 of the second rotor 430.

In one embodiment, the distance d2 between the first line L1 and thethird line L3 may be calculated by Equation 2 below.e*1.25<d2<e*1.35  [Equation 2]

Here, e represents the distance between the center P1 of the first rotor410 and the center P2 of the second rotor 430.

Therefore, the arrangement position of the third protrusion 523 of thesecond suction port 520 may be determined by the number N of gear teethof the first rotor 410 and a distance e between the center P1 of thefirst rotor 410 and the center P2 of the second rotor 430.

FIG. 16 is a diagram showing a change in flow rate performance when theshape of the second cover of FIG. 15 is applied.

Referring to FIG. 16 , in the related art, an increase in flow ratedecreased when the speed of rotation was 4000 rpm or more and decreasedgreatly when the speed of rotation exceeded 5000 rpm.

However, when the shape of the second cover 500 according to anembodiment of the present invention was applied, a constant flow rateincrease was secured even when the speed of rotation exceeded 4000 rpmand was continuously maintained even when the speed of rotation exceeded5000 rpm.

FIG. 17 is a longitudinal sectional view of a motor according to theembodiment. FIG. 18 is a cross sectional view taken along line A-A ofFIG. 17 .

Referring to FIGS. 17 and 18 , a motor 1001 according to an embodimentmay include a housing 1100, a bracket 1200, a rotor 1300, a stator 1400,and a shaft 1500. Here, the bracket 1200 may be disposed to cover anopen upper portion of the housing 1100.

The housing 1100 and the bracket 1200 may form an exterior of the motor1001. Here, the housing 1100 may be formed in a cylindrical shape havingan opening thereon.

Therefore, an accommodation space may be formed in the motor 1101 due tocoupling of the housing 1100 and the bracket 1200. As illustrated inFIG. 17 , the rotor 1300, the stator 1400, the shaft 1500, and the likemay be disposed in the accommodation space.

The housing 1100 may be formed in a cylindrical shape so that the stator1400 may be supported on an inner circumferential surface of the housing1100. A pocket portion for accommodation of a bearing 1060 supporting alower portion of the shaft 1500 may be provided at the bottom of thehousing 1100.

The bracket 1200 disposed on the top of the housing 1100 may also beprovided with a pocket portion for supporting an upper portion of theshaft 1500. The bracket 1200 may include a hole or a groove into which aconnector, to which an external cable is connected, is inserted.

The rotor 1300 is disposed inside the stator 1400. Here, an inner sidewith respect to a radial direction (a y-axis direction) refers to adirection toward a center CC with respect to the center CC, and an outerside refers to a direction opposite that of the inner side. The centerCC is the center of rotation of the shaft 1500 and may be a center CC ofthe rotor 1300.

The rotor 1300 may include a rotor core 1310 and a magnet 1320.

Here, the rotor 1300 may be an interior permanent magnet (IPM) typerotor in which the magnet 1320 is coupled to the inside of the rotorcore 1310. Accordingly, the rotor 1300 may include a pocket into whichthe magnet 1320 is inserted.

FIG. 19 is a diagram illustrating a rotor core of a motor according toan embodiment.

Referring to FIG. 19 , a rotor core 1310 may include a main body 1311, apocket 1312, a first barrier 1313, a second barrier 1314, and a hole1315.

The main body 1311 forms an exterior of the rotor core 1310.

Here, the main body 1311 may be formed by stacking a plurality of thinsteel plates together.

A magnet 1320 is disposed in the pocket 1312.

As illustrated in FIG. 19 , a plurality of pockets 1312 may be formed tobe spaced apart from each other in a circumferential direction withrespect to a center CC of the rotor core 1310. Accordingly, magnets 1320may be disposed in the circumferential direction with respect to thecenter CC of the rotor core 1310. In this case, the magnets 1320 may beinserted into the pockets 1312.

The first barrier 1313 may extend from both sides of the pocket 1312. Asillustrated in FIG. 18 , when the magnets 1320 are disposed in thepockets 1312, the first barriers 1313 may be disposed at both sides ofthe magnets 1320.

An air layer may be formed on the first barrier 1313. Accordingly, thefirst barrier 1313 serves as a flux barrier to prevent a short circuitand a leakage of magnetic flux.

However, when only the first barrier 1313 is disposed on the main body1311 without the second barrier 1314, the magnet 1320 may not be fullymagnetized when the magnet 1320 is magnetized using only a certainamount of a current. Here, the magnetization refers to applying, to amagnet, an external magnetic field about 3 to 4 times a coercive forceof the magnet. In this case, a high current is used to generate theexternal magnetic field. In particular, when the magnet is anNdFeB-based rare earth magnet, a peak value of a magnetizing field isdetermined by saturation magnetic flux density.

When a certain current is applied, the second barrier 1314 adjustsmagnetic flux saturation of the main body 1311 so that a maximum H fieldmay be present in the magnet 1320. Accordingly, the magnet 1320 may befully magnetized.

FIG. 20 is a diagram illustrating region B of FIG. 18 , and the region Bis part of the rotor 1300.

Referring to FIGS. 18 and 20 , a plurality of second barriers 1314 maybe arranged in the circumferential direction. For example, two secondbarriers 1314 may be arranged adjacent to one magnet 1320. Here, thearrangement of the two second barriers 1314 adjacent to one magnet 1320may be understood to mean that the second barriers 1314 are arrangedsuch that outer circumferential surfaces thereof are spaced a certaindistance from the magnet 1320.

The second barriers 1314 may be formed between an inner circumferentialsurface 311 a and an outer circumferential surface 311 b of the mainbody 1311. As illustrated in FIG. 20 , the second barriers 1314 may beformed between the inner circumferential surface 311 a of the main body1311 and an inner side 321 of the magnet 1320.

The second barrier 1314 may be formed to have a circular cross sectionhaving a certain radius R. That is, a size of the second barrier 1314may be defined by the radius R. Here, an example in which the secondbarrier 1314 has a circular cross section has been described above butembodiments are not limited thereto. As illustrated in FIG. 21 , thesecond barrier 1314 may be provided as a polygonal shape, such as ahemispherical shape, an ellipse shape, a tetragonal shape or a hexagonalshape, or a bent tetragonal shape in consideration of an arrangementposition of the second barrier 1314.

The second barriers 1314 may be disposed to be symmetric to each otherwith respect to a first line L11. As illustrated in FIG. 20 , two secondbarriers 1314 disposed to correspond to one magnet 1320 may be symmetricto each other with respect to the first line L11. Here, the first lineL11 is a line passing through the center CC of the main body 1311 andthe center of a width W of the magnet.

The arrangement position of the second barrier 1314 may be defined by anarrangement angle θ and an arrangement distance D33 from the center CCof the rotor core 1310.

A center C11 of the second barrier 1314 may have a certain arrangementangle θ with respect to the first line L11 in the circumferentialdirection. For example, the arrangement angle θ may be an angle formedby the first line L11 and a second line L22 passing through the centerCC of the main body 1311 and the center C11 of the second barrier 1314.In this case, an included angle between the first line L11 and thesecond line L22 is an angle with respect to the center CC.

In this case, the inner side 1321 of the magnet 1320 may be disposed onthe second line L22 passing through the center CC of the main body 1311and the center C11 of the second barrier 1314. As illustrated in FIG. 20, one point P1 on the outer circumferential surface of the secondbarrier 1314 and one point P2 on the inner side 321 of the magnet 1320may be disposed on the second line L22.

The arrangement angle θ may be calculated by Equation 3 below.

$\begin{matrix}{{\arctan\left( \frac{W/2}{D11} \right)} \leq \theta \leq {\arctan\left( \frac{W/2}{D22} \right)}} & \left\lbrack {{Equation}3} \right\rbrack\end{matrix}$

As illustrated in FIG. 20 , W represents a width of a magnet, D11represents the distance from the center of a main body to an inner sidesurface of the magnet, and D22 represents the distance from the centerof the main body to an outer side surface of the magnet.

For example, when the rotor 1300, which is an IPM type, is designed, thearrangement angle θ is less than 25.3 degrees and greater than 20.7degrees when W is 9.8 mm, D11 is 10.375 mm, and D22 is 12.95 mm.Accordingly, the arrangement angle θ of the second barrier 1314 may bedesigned to be an angle between 20.7 degrees and 25.3 degrees.

The arrangement distance D33 may be calculated by Equation 4 below.Here, the arrangement distance D33 is a distance from the center CC ofthe main body 1311 to the center of the second barrier 1314.

$\begin{matrix}{{{D33} = \frac{D11}{\cos\theta}} - O - R} & \left\lbrack {{Equation}4} \right\rbrack\end{matrix}$

As illustrated in FIG. 20 , O represents the distance between one pointP1 on the outer circumferential surface of the second barrier 1314 andone point P2 on the inner side 321 of the magnet 1320, which are locatedon the second line L22.

As described above, when the arrangement angle θ is set to 22 degrees tobe within a range of the arrangement angle θ, R is set to 0.5 mm, and Ois set to 0.2 mm, which are design parameters, the arrangement distanceD33 is determined to be 10.5 mm according to Equation 4 above.

Therefore, the arrangement position of the second barrier 1314 isdetermined by the placement angle θ of 22 degrees and the placementdistance D33 of 10.5 mm.

When the arrangement angle θ is set to 21.5 degrees to be within therange of the arrangement angle θ and design parameters R and O arerespectively set to 1.0 mm and 0.4 mm, the arrangement distance D33 isdetermined to be 9.75 mm according to Equation 4 above.

Therefore, the arrangement position of the second barrier 1314 isdetermined by the placement angle θ of 21.5 degrees and the placementdistance D33 of 9.75 mm.

The second barrier 1314 may be formed to be long from an upper end ofthe main body 1311 to a lower end of the main body 1311. However, thepresent invention is not limited thereto, and a length of the secondbarrier 1314 in an axial direction (an x-axis direction) may be the sameas a length of the magnet 1320 in the axial direction (the x-axisdirection). Here, an air layer may be formed on the second barrier 1314.

The hole 1315 may be formed in a central portion of the body 315.Accordingly, the shaft 1500 may be coupled to the hole 1315.

The magnet 1320 may be provided in the form of a tetragonal pillarextending from the upper end of the rotor core 1310 to the lower end ofthe rotor core 1310. An example in which six magnets 1320 are disposedin the motor 1001 has been described above, but the embodiments are notlimited thereto.

In this case, the magnitude of an external magnetic field required tomagnetize the magnets 1320 varies according to energy density, coerciveforce, saturation magnetic flux density, etc. of a material of themagnets 1320.

FIG. 22 is a diagram showing a comparison of an H field with respect toa rotor of a motor according to an example with an H field with respectto a rotor of a motor according to a comparative example. FIG. 22A is adiagram illustrating the H field of the motor according to the example,and FIG. 22B is a diagram illustrating the H field of the motoraccording to the comparative example. Here, a motor 1002 provided as thecomparative example is different from the motor 1001 in terms of thepresence of and an arrangement position of the second barrier 314.

Referring to FIG. 22 , when a magnetization peak current of 10.26 kA issupplied to the motor 1001 and the motor 1002 of the comparativeexample, an H field of the magnet 1320 of the motor 1001 is1.8734*10{circumflex over (6)} A/m and an H field of the motor 1002 ofthe comparative example is 1.6465*10{circumflex over (6)} A/m. In thiscase, the radius R of the second barrier 1314 is 1.0 mm.

That is, in the case of the motor 1001, a magnitude of the H field isincreased by about 13.8% due to the second barrier 1314. Accordingly, amagnetizing current of the motor 1001 may be reduced from 10.26 kA to8.84 kA. That is, the motor 1002 of the comparative example to which10.26 kA is applied and the motor 1001 to which 8.84 kA is applied havethe same magnetization performance.

Therefore, the lowest H field of the motor 1001 with the second barrier1314 increases and thus magnetization power of the motor 1001 isimproved compared to the motor 1002 of the comparative example. Inaddition, a local non-magnetized region of the magnet 1320 decreases.

Meanwhile, the H field may be adjusted by the radius R of the secondbarrier 1314. That is, as the radius R of the second barrier 1314 isadjusted, the arrangement distance D3 is adjusted and thus amagnetization performance difference occurs.

When the radius R of the second barrier 1314 is adjusted to 0.5 mm and amagnetizing peak current of 10.26 kA is supplied to the motor 1001 andthe motor 1002 of the comparative example, an H field of the magnet 1320of the motor 1001 is 1.8288*10{circumflex over (6)} A/m and an H fieldof the motor 1002 of the comparative example is 1.6465*10{circumflexover (6)} A/m.

That is, in the case of the motor 1001, the magnitude of the H field isimproved by about 11.1% due to the second barrier 1314.

Accordingly, the second barrier 1314 of the motor 1001 may increase themagnitude of a magnetization field in the magnet 1320, therebyincreasing a magnetization feature of the magnet 1320. In addition, thearrangement distance D3 is adjusted by the radius R of the secondbarrier 1314.

FIG. 23 is a diagram showing a comparison of a uniform magnetic fluxline of a rotor of a motor according to an example with a uniformmagnetic flux line of a rotor of a motor according to a comparativeexample. FIG. 23A is a diagram illustrating the uniform magnetic fluxline of the motor of the example, and FIG. 23B is a diagram illustratingthe uniform magnetic flux line of the motor of the comparative example.

Referring to FIG. 23 , a second barrier 1314 of a motor 1001 causes achange in magnetic resistance to change a magnetic flux path. Inparticular, the second barrier 1314 with an air layer has lowpermeability and thus a magnetic flux path in the rotor core 1310 may begreatly changed. Accordingly, a magnetic flux is concentrated at aninner edge of the magnet 1320 and thus the motor 1001 has a highermagnetic flux density distribution than the motor 1002 of thecomparative example.

FIG. 24 is a diagram showing a comparison of magnetic flux density of arotor of a motor according to an example with magnetic flux density of arotor of a motor according to a comparative example. FIG. 24A is adiagram illustrating an H field of the motor of the example, and FIG.24B is a diagram illustrating an H field of the motor of comparativeexample.

Referring to FIG. 24 , the lowest magnetic flux density of the motor1001 is higher than that of the motor 1002 of the comparative example.Accordingly, a magnitude of an external magnetic field applied to aninner corner of the magnet 1320 increases.

The stator 1400 may be supported by the inner circumferential surface ofthe housing 1100. The stator 1400 is disposed outside the rotor 1300.That is, the rotor 1300 may be disposed on an inner side of the stator1400.

Referring to FIGS. 17 and 18 , the stator 1400 may include a stator core1410 and a coil 1420. Here, the stator core 1410 may be formed bystacking a plurality of thin steel plates together. Alternatively, thestator core 1410 may be formed by coupling or connecting a plurality ofsplit cores to each other.

The stator core 1410 may include a yoke 1411 and teeth 1412.

The yoke 1411 may be formed in a cylindrical shape.

The teeth 1412 may be disposed to protrude from the yoke 1411 toward thecenter CC. As illustrated in FIG. 20 , the teeth 1412 may be disposed atregular intervals along an inner circumferential surface of the yoke1411 to protrude toward the center CC. That is, the teeth 1412 may bedisposed along the inner circumferential surface of the yoke 1411 to bespaced a certain distance from each other.

A coil 1420 may be wound around the teeth 1412. In this case, aninsulator 1430 may be disposed on the tooth 1412. The insulator 1430insulates the teeth 1412 and the coil 1420 from each other.

A current may be applied to the coil 1420. Accordingly, electricalinteraction with the magnet 1320 of the rotor 1300 may be caused torotate the rotor 1300. When the rotor 1300 rotates, the shaft 1500 alsorotates. In this case, the shaft 1500 may be supported by the bearing1060.

The shaft 1500 may be coupled to the rotor 1300. When electromagneticinteraction occurs between the rotor 1300 and the stator 1400 throughthe supply of current, the rotor 1300 rotates and the rotation shaft1500 rotates in association with the rotor 1300.

Meanwhile, the motor 1001 may further include a sensing magnet assembly1600 to identify the position of the rotor 1300.

The sensing magnet assembly 1600 may include a sensing magnet and asensing plate. The sensing magnet and the sensing plate can be combinedto have the same axis.

The sensing magnet may include a main magnet disposed in acircumferential direction to be adjacent to a hole forming an innercircumferential surface thereof, and a sub-magnet formed at an edgethereof. The main magnet may be arranged in the same manner as a drivemagnet inserted into the rotor 1300 of the motor 1001. The sub-magnet issubdivided to have a larger number of poles than the main magnet.Therefore, a rotation angle may be more subdivided and measured, and themotor 1001 may be more smoothly driven.

The sensing plate may be formed of a disc type metal material. An upperside of the sensing plate may be coupled to the sensing magnet. Inaddition, the sensing plate may be coupled to the shaft 1500. Here, thesensing plate is provided with a hole through which the shaft 1500passes.

In addition, the motor 1001 may further include a printed circuit board1700 on which a sensor is disposed to sense a magnetic force of thesensing magnet.

In this case, the sensor may be a Hall IC. The sensor senses a change ofN and S poles of the main magnet or the sub-magnet to generate a sensingsignal. In the case of a three-phase brushless motor, at least threesensing signals are required to obtain information about U-, V-, andW-phases and thus at least three sensors may be arranged.

The printed circuit board 1700 may be coupled to a bottom surface of thebracket 1200 and installed on the sensing magnet assembly 1600 such thatthe sensor faces the sensing magnet.

Embodiments of the present invention have been described above in detailwith reference to the accompanying drawings.

While the technical idea of the present invention has been describedabove with respect to examples thereof, it will be apparent to those ofordinary skill in the art that various modifications, changes andalternatives may be made without departing from the essential featuresof the invention. Therefore, the embodiments disclosed herein and theaccompanying drawings are not intended to restrict the scope of thepresent invention and are only used for a better understanding of thepresent invention. The scope of the present invention is not limited bythese embodiments and the accompanying drawings. The scope of protectionof the present invention should be interpreted based on the followingclaims, and all technical ideas within a scope equivalent thereto shouldbe construed as falling within the scope of the present invention.

DESCRIPTION OF REFERENCE NUMERALS

1: electric pump, 100: motor unit, 110: shaft, 111: cut surface, 120:rotor, 130: stator, 131: coil, 140: bus bar, 141: bus bar body, 141 a:first protrusion, 143: bus bar terminal, 143 a: connection terminal, 143b: curved portion, 150: motor housing, 151: protrusion, 151 a: hole,200: connector unit, 210: connector body, 211: first through hole, 230:connector connection part, 231: first connection portion, 231 a: secondprotrusion, 231 b: rib, 231 c: groove, 233: second connection portion,250: power terminal, 251: contact portion, 300: first cover, 310: firstsurface, 320: first suction port, 330: first discharge port, 340: secondthrough hole, 400: pump unit, 410: first rotor, 411: first lobe, 430:second rotor, 431: second lobe, 440: third coupling hole, 500: secondcover, 510: second surface, 520: second suction port, 521: inlet, 523:third protrusion, 530: second discharge port, 531: outlet, 1001: motor,1060: bearing, 1100: housing, 1200: bracket, 1300: rotor, 1310: rotorcore, 1311: main body, 1312: pocket, 1313: first barrier, 1314: secondbarrier, 1315: hole, 1320: magnet, 1400: stator, 1410: stator core,1411: yoke, 1412: tooth, 1420: coil, 1500: shaft, 1600: sensing magnetassembly, 1700: printed circuit board

The invention claimed is:
 1. A motor comprising: a shaft; a rotorincluding a hole in which the shaft is disposed; and a stator outsidethe rotor, wherein the rotor comprises a rotor core and a magnet,wherein the rotor core comprises: a main body; a pocket which is formedin the main body and in which the magnet is disposed; first barriersextending from both sides of the pocket; and second barriers formedbetween an inner circumferential surface of the main body and an outercircumferential surface of the main body, wherein a center (C11) of thesecond barrier has a certain arrangement angle (θ) in a circumferentialdirection from a first line (L11) passing through a center (CC) of themain body and a center of a width (W) of the magnet, wherein thearrangement angle (θ) is calculated by the following equation:${{{arc}\tan\left( \frac{W/2}{D11} \right)} \leq \theta \leq {{arc}\tan\left( \frac{W/2}{D22} \right)}},$wherein W represents a width of the magnet, D11 represents a distancefrom the center of the main body to an inner side surface of the magnet,and D22 represents a distance from the center of the main body to anouter side surface of the magnet.
 2. The motor of claim 1, wherein thesecond barrier is formed to be long from an upper end of the main bodyto a lower end of the main body.
 3. The motor of claim 1, wherein two ofthe second barriers disposed to correspond to one magnet are symmetricalwith respect to the first line (L11).
 4. The motor of claim 1, whereinthe second barrier has a certain radius (R).
 5. The motor of claim 4,wherein the inner side surface of the magnet is disposed on a secondline (L22) passing through the center (CC) of the main body and thecenter (C11) of the second barrier.
 6. The motor of claim 5, wherein anarrangement distance (D33) from the center (CC) of the main body to thecenter (C11) of the second barrier is calculated by the followingequation: ${{D3} = {\frac{D1}{\cos\theta} - O - R}},$ wherein Orepresents a distance between one point (P1) on an outer circumferentialsurface of the second barrier disposed on the second line (L22) and onepoint P2 on the inner side surface of the magnet.
 7. A motor comprising:a rotor including a hole in which a shaft is to be disposed; and astator outside the rotor, wherein the rotor comprises a rotor core and aplurality of magnets, wherein the rotor core includes: a body; aplurality of pockets disposed at the body configured to receive theplurality of magnets; a plurality of first barriers, and a first one ofthe first barriers to extend from a first one of the pockets thatreceives a first one of the magnets, and a second one of the firstbarriers to extend from the first one of the pockets; and a plurality ofsecond barriers formed on the body, a first one of the second barriershaving a radius of a circular shape, wherein a center of the first oneof the second barriers has a specific arrangement angle (θ) in acircumferential direction from a first line passing through a center ofthe body and a center of a width (W) of the first one of the magnets,wherein the specific arrangement angle (θ) is determined by thefollowing equation:${{{arc}\tan\left( \frac{W/2}{D11} \right)} \leq \theta \leq {{arc}\tan\left( \frac{W/2}{D22} \right)}},$wherein W represents a width of the first one of the magnets, D11represents a minimum distance from the center of the body to an innerside surface of the first one of the magnets, and D22 represents aminimum distance from the center of the body to an outer side surface ofthe first one of the magnets.
 8. The motor of claim 7, wherein the innerside surface of the first one of the magnets is disposed on a secondline passing through the center of the body and the center of the firstone of the second barriers.
 9. The motor of claim 8, wherein anarrangement distance from the center of the body to the center of thefirst one of the second barriers is determined by the followingequation: ${{D3} = {\frac{D1}{\cos\theta} - O - R}},$ wherein Orepresents a distance between one point on an outer circumferentialsurface of the first one of the second barriers disposed on the secondline and one point on the inner side surface of the first one of themagnets.
 10. The motor of claim 7, wherein the first one of the secondbarriers is formed to be long from an upper end of the body to a lowerend of the body.
 11. The motor of claim 7, wherein two of the secondbarriers disposed to correspond to the first one of the magnets aresymmetrical with respect to the first line.